Battery heating circuits and methods with resonance components in series using voltage inversion and freewheeling circuit components

ABSTRACT

Circuit and method for heating a battery. The circuit includes the battery with damping component, a switch unit, a switching control module, an energy storage circuit, a freewheeling circuit, and an energy superposition unit. The energy storage circuit connects with the battery to form a loop, and includes current and charge storage components. The damping component, switch unit, current storage component, and charge storage component connect in series. The switching control module turns on the switch unit such that current flows between the battery and energy storage circuit. The energy superposition unit superposes the energy in the energy storage circuit with the energy in the battery after the switch unit switches on and then off. The freewheeling circuit forms a serial loop with the battery and the current storage component to sustain current flow in the battery after the switch unit switches on and then off.

1. CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201010245288.0, filed Jul. 30, 2010, Chinese Patent Application No.201010274785.3, filed Aug. 30, 2010, and Chinese Patent Application No.201110134005.X, filed May 23, 2011, all these three applications beingincorporated by reference herein for all purposes.

Additionally, this application is related to International ApplicationPublication No. WO2010/145439A1 and Chinese Application Publication No.CN102055042A, both these two applications being incorporated byreference herein for all purposes.

2. BACKGROUND OF THE INVENTION

The present invention pertains to electric and electronic field, inparticular related to a battery heating circuit.

Considering cars need to run under complex road conditions andenvironmental conditions or some electronic devices are used under harshenvironmental conditions, the battery, which serves as the power supplyunit for electric-motor cars or electronic devices, need to be adaptiveto these complex conditions. In addition, besides these conditions, theservice life and charge/discharge cycle performance of the battery needto be taken into consideration; especially, when electric-motor cars orelectronic devices are used in low temperature environments, the batteryneeds to have outstanding low-temperature charge/discharge performanceand higher input/output power performance.

Usually, under low temperature conditions, the resistance of the batterywill increase, and so will the polarization; therefore, the capacity ofthe battery will be reduced.

To keep the capacity of the battery and improve the charge/dischargeperformance of the battery under low temperature conditions, someembodiments of the present invention provide a battery heating circuit.

3. BRIEF SUMMARY OF THE INVENTION

The objective of certain embodiments of the present invention is toprovide a battery heating circuit, in order to solve the problem ofdecreased capacity of the battery caused by increased resistance andpolarization of the battery under low temperature conditions.

The battery heating circuit provided in certain embodiments of thepresent invention comprises a switch unit, a switching control module, adamping component, an energy storage circuit, a freewheeling circuit,and an energy superposition unit, the energy storage circuit isconfigured to connect with the battery to form a loop, and comprises acurrent storage component and a charge storage component; the dampingcomponent, the switch unit, the current storage component, and thecharge storage component are connected in series; the switching controlmodule is connected with the switch unit, and is configured to controlON/OFF of the switch unit, so as to control the energy flowing betweenthe battery and the energy storage circuit; the energy superpositionunit is connected with the energy storage circuit, and is configured tosuperpose the energy in the energy storage circuit with the energy inthe battery when the switch unit switches on and then switches off; thefreewheeling circuit is configured to form a serial loop with thebattery and the current storage component to sustain current flow in thebattery after the switch unit switches on and then switches off.

The heating circuit provided in certain embodiments of the presentinvention can improve the charge/discharge performance of the battery;in addition, since the energy storage circuit is connected with thebattery in series in the heating circuit, safety problem related withfailures and short circuit caused by failures of the switch unit can beavoided when the battery is heated due to the existence of the chargestorage component connected in series, and therefore the battery can beprotected effectively.

In addition, owing to the existence of the current storage component inthe loop, switching off the switch unit when there is current flow inthe loop will cause abrupt current drop to zero and therefore induceshigh induced voltage on the current storage component in the loop, whichmay cause damage to other circuit components in the loop (e.g., theswitch unit). In the heating circuit provided in certain embodiments ofthe present invention, since the current flow in the battery can besustained by the freewheeling circuit, the current flow in the currentstorage component will have no abrupt change when the switch unitswitches off, and thus no high voltage will be induced when the switchunit switches off; as a result, damage to the switch unit resulted fromhigh induced voltage on the current storage component in the loop can beprevented, and the heating circuit is safer, and the adverse effect tothe entire circuit can be reduced.

In addition, an energy superposition unit is provided in the heatingcircuit in certain embodiments of the present invention, and the energysuperposition unit can superpose the energy in the energy storagecircuit with the energy in the battery after the switch unit switches onand then switches off; thus, the discharging current in the heating loopwill be increased when the switch unit is controlled to switch on at thenext time, and therefore the working efficiency of the heating circuitis improved.

Other characteristics and advantages of the present invention will befurther described in detail in the following section for embodiments.

4. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, as a part of this description, are providedhere to facilitate further understanding of the present invention, andare used in conjunction with the following embodiments to explain thepresent invention, but shall not be comprehended as constituting anylimitation on the present invention. In the figures:

FIG. 1 is a schematic diagram of the battery heating circuit provided inone embodiment of the present invention;

FIG. 2 is a schematic diagram of one embodiment of the switch unit shownin FIG. 1;

FIG. 3 is a schematic diagram of one embodiment of the switch unit shownin FIG. 1;

FIG. 4 is a schematic diagram of one embodiment of the switch unit shownin FIG. 1;

FIG. 5 is a schematic diagram of one embodiment of the switch unit shownin FIG. 1;

FIG. 6 is a schematic diagram of one embodiment of the switch unit shownin FIG. 1;

FIG. 7 is a schematic diagram of one embodiment of the freewheelingcircuit shown in FIG. 1;

FIG. 8 is a schematic diagram of another embodiment of the freewheelingcircuit shown in FIG. 1;

FIG. 9 is a schematic diagram of one embodiment of the energysuperposition unit shown in FIG. 1;

FIG. 10 is a schematic diagram of one embodiment of the polarityinversion unit shown in FIG. 9;

FIG. 11 is a schematic diagram of one embodiment of the polarityinversion unit shown in FIG. 9;

FIG. 12 is a schematic diagram of one embodiment of the polarityinversion unit shown in FIG. 9;

FIG. 13 is a schematic diagram of one embodiment of the first DC-DCmodule shown in FIG. 12;

FIG. 14 is a schematic diagram of one embodiment of the battery heatingcircuit provided in the present invention;

FIG. 15 is a schematic diagram of one embodiment of the energyconsumption unit shown in FIG. 14;

FIG. 16 is a schematic diagram of one embodiment of the battery heatingcircuit provided in the present invention;

FIG. 17 is a timing sequence diagram of the waveform corresponding tothe heating circuit shown in FIG. 16;

FIG. 18 is a schematic diagram of one embodiment of the battery heatingcircuit provided in the present invention;

FIG. 19 is a timing sequence diagram of the waveform corresponding tothe heating circuit shown in FIG. 18;

FIG. 20 is a schematic diagram of one embodiment of the battery heatingcircuit provided in the present invention; and

FIG. 21 is a timing sequence diagram of the waveform corresponding tothe heating circuit shown in FIG. 20.

5. DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the present invention are described in detailbelow, with reference to the accompanying drawings. It should beappreciated that the embodiments described here are only provided todescribe and explain the present invention, but shall not be deemed asconstituting any limitation on the present invention.

It is noted that, unless otherwise specified, when mentioned hereafterin this description, the term “switching control module” may refer toany controller that can output control commands (e.g., pulse waveforms)under preset conditions or at preset times and thereby control theswitch unit connected to it to switch on or switch off accordingly,according to some embodiments. For example, the switching control modulecan be a PLC. Unless otherwise specified, when mentioned hereafter inthis description, the term “switch” may refer to a switch that enablesON/OFF control by using electrical signals or enables ON/OFF control onthe basis of the characteristics of the component according to certainembodiments. For example, the switch can be either a one-way switch(e.g., a switch composed of a two-way switch and a diode connected inseries, which can be conductive in one direction) or a two-way switch(e.g., a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) oran IGBT with an anti-LAI-parallel freewheeling diode). Unless otherwisespecified, when mentioned hereafter in this description, the term“two-way switch” may refer to a switch that can be conductive in twodirections, which can enable ON/OFF control by using electrical signalsor enable ON/OFF control on the basis of the characteristics of thecomponent according to some embodiments. For example, the two-way switchcan be a MOSFET or an IGBT with an anti-parallel freewheeling diode.Unless otherwise specified, when mentioned hereafter in thisdescription, the term “one-way semiconductor component” may refer to asemiconductor component that can be conductive in one direction, such asa diode, according to certain embodiments. Unless otherwise specified,when mentioned hereafter in this description, the term “charge storagecomponent” may refer to any device that can enable charge storage, suchas a capacitor, according to some embodiments. Unless otherwisespecified, when mentioned hereafter in this description, the term“current storage component” may refer to any device that can storecurrent, such as an inductor, according to certain embodiments. Unlessotherwise specified, when mentioned hereafter in this description, theterm “forward direction” may refer to the direction in which the energyflows from the battery to the energy storage circuit, and the term“reverse direction” may refer to the direction in which the energy flowsfrom the energy storage circuit to the battery, according to someembodiments. Unless otherwise specified, when mentioned hereafter inthis description, the term “battery” may comprise primary battery (e.g.,dry battery or alkaline battery, etc.) and secondary battery (e.g.,lithium-ion battery, nickel-cadmium battery, nickel-hydrogen battery, orlead-acid battery, etc.), according to certain embodiments. Unlessotherwise specified, when mentioned hereafter in this description, theterm “damping component” may refer to any device that inhibits currentflow and thereby enables energy consumption, such as a resistor, etc.,according to some embodiments. Unless otherwise specified, whenmentioned hereafter in this description, the term “main loop” may referto a loop composed of battery, damping component, switch unit and energystorage circuit connected in series according to certain embodiments.

It should be noted specially that, considering different types ofbatteries have different characteristics, in some embodiments of thepresent invention, “battery” may refer to an ideal battery that does nothave internal parasitic resistance and parasitic inductance or has verylow internal parasitic resistance and parasitic inductance, or may referto a battery pack that has internal parasitic resistance and parasiticinductance; therefore, those skilled in the art should appreciate thatif the battery is an ideal battery that does not have internal parasiticresistance and parasitic inductance or has very low internal parasiticresistance and parasitic inductance, the damping component R1 may referto a damping component external to the battery and the current storagecomponent L1 may refer to a current storage component external to thebattery; if the battery is a battery pack that has internal parasiticresistance and parasitic inductance, the damping component R1 may referto a damping component external to the battery or refer to the parasiticresistance in the battery pack, and the current storage component L1 mayrefer to a current storage component external to the battery or refer tothe parasitic inductance in the battery pack, according to certainembodiments.

To ensure the normal service life of the battery, according to someembodiments, the battery can be heated under low temperature condition,which is to say, when the heating condition is met, the heating circuitis controlled to start heating for the battery; when the heating stopcondition is met, the heating circuit is controlled to stop heating,according to certain embodiments.

In the actual application of battery, the battery heating condition andheating stop condition can be set according to the actual ambientconditions, to ensure normal charge/discharge performance of thebattery, according to some embodiments.

To heat up the battery E in a low temperature environment, oneembodiment of the present invention provides a heating circuit forbattery E, as shown in FIG. 1; the heating circuit comprises a switchunit 1, a switching control module 100, a damping component R1, anenergy storage circuit, a freewheeling circuit 20, and an energysuperposition unit, the energy storage circuit is configured to connectwith the battery to form a loop, and comprises a current storagecomponent L1 and a charge storage component C1; the damping componentR1, the switch unit 1, the current storage component L1, and the chargestorage component C1 are connected in series; the switching controlmodule 100 is connected with the switch unit 1, and is configured tocontrol ON/OFF of the switch unit 1, so as to control the energy flowingbetween the battery and the energy storage circuit; the energysuperposition unit is connected with the energy storage circuit, and isconfigured to superpose the energy in the energy storage circuit withthe energy in the battery when the switch unit 1 switches on and thenswitches off; the freewheeling circuit 20 is configured to form a serialloop with the battery and the current storage component L1 to sustaincurrent flow in the battery after the switch unit 1 switches on and thenswitches off.

With the technical scheme of certain embodiments of the presentinvention, when the heating condition is met, the switching controlmodule 100 controls the switch unit 1 to switch on, and thus the batteryE is connected with the energy storage circuit in series to form a loop,and can discharge through the loop (i.e., charge the charge storagecomponent C1); when the current in the loop reaches zero in normaldirection after the peak current, the charge storage component C1 beginsto discharge through the loop, i.e., charge the battery E; in thecharge/discharge process of the battery E, the current in the looppasses through the damping component R1 in both normal direction andreversed direction, and thus the battery E is heated up by the heatgenerated in the damping component R1; when the condition for heatingstop is met, the switching control module 100 can control the switchunit 1 to switch off, so that the heating circuit stops heating.

To achieve to-and-fro energy flow between the battery E and the energystorage circuit, in one embodiment of the present invention, the switchunit 1 is a two-way switch K3, as shown in FIG. 2. The switching controlmodule 100 controls ON/OFF of the two-way switch K3; when the battery Eis to be heat up, the two-way switch K3 can be controlled to switch on;if heating is to be paused or is not needed, the two-way switch K3 canbe controlled to switch off.

Employing a separate two-way switch K3 to implement the switch unit 1can simplify the circuit, reduce system footprint, and simplify theimplementation; however, to implement cut-off of reverse current, thefollowing embodiment of the switch unit 1 is further provided in thepresent invention.

Preferably, the switch unit 1 comprises a first one-way branchconfigured to enable energy flow from the battery E to the energystorage circuit, and a second one-way branch configured to enable energyflow from the energy storage circuit to the battery E; wherein: theswitching control module 100 is connected to the first one-way branchand the second one-way branch respectively, and is configured to controlON/OFF the switch unit 1 by controlling ON/OFF of the connectedbranches.

When the battery is to be heated, both the first one-way branch and thesecond one-way branch can be controlled to switch on; when heating is tobe paused, either or both of the first one-way branch and the secondone-way branch can be controlled to switch off; when heating is notneeded, both of the first one-way branch and the second one-way branchcan be controlled to switch off. Preferably, both of the first one-waybranch and the second one-way branch are subject to the control of theswitching control module 100; thus, energy flow cut-off in normaldirection and reversed direction can be implemented flexibly.

In another embodiment of the switch unit 1, as shown in FIG. 3, theswitch unit 1 comprises a two-way switch K4 and a two-way switch K5,wherein: the two-way switch K4 and two-way switch K5 are connected inseries opposite to each other, to form the first one-way branch and thesecond one-way branch; the switching control module 100 is connectedwith the two-way switch K4 and the two-way switch K5 respectively, tocontrol ON/OFF of the first one-way branch and the second one-way branchby controlling ON/OFF of the two-way switch K4 and two-way switch K5.

When the battery E is to be heated, the two-way switches K4 and K5 canbe controlled to switch on; when heating is to be paused, either or bothof the two-way switch K4 and the two-way switch K5 can be controlled toswitch off; when heating is not needed, both of the two-way switch K4and the two-way switch K5 can be controlled to switch off. In such animplementation of switch unit 1, the first one-way branch and the secondone-way branch can be controlled separately to switch on and off, andtherefore energy flow in normal direction and reversed direction in thecircuit can be implemented flexibly.

In another embodiment of switch unit 1, as shown in FIG. 4, the switchunit 1 comprises a switch K6, a one-way semiconductor component D11, aswitch K7, and a one-way semiconductor component D12, wherein: theswitch K6 and the one-way semiconductor component D11 are connected inseries with each other to form the first one-way branch; the switch K7and the one-way semiconductor component D12 are connected in series witheach other to form the second one-way branch; the switching controlmodule 100 is connected with the switch K6 and the switch K7, to controlON/OFF of the first one-way branch and the second one-way branch bycontrolling ON/OFF of the switch K6 and the switch K7. In the switchunit 1 shown in FIG. 4, since switches (i.e., the switch K6 and theswitch K7) exist in both one-way branches, energy flow cut-off functionin normal direction and reversed direction is implemented.

Preferably, the switch unit 1 can further comprise a resistor, which isconnected in series with the first one-way branch and/or second one-waybranch and configured to reduce the current in the heating circuit forthe battery E and avoid damage to the battery E resulted fromover-current in the circuit. For example, a resistor R6 connected inseries with the two-way switch K4 and the two-way switch K5 can be addedin the switch unit 1 shown in FIG. 3, to obtain another implementationof the switch unit 1, as shown in FIG. 5. FIG. 6 shows one embodiment ofthe switch unit 1, which is obtained by connecting the resistor R2 andthe resistor R3 in series in the two one-way branches in the switch unit1 shown in FIG. 4, respectively.

As known by those skilled in the art, any circuit device has a voltagerating, which is the standard operating voltage that the circuit devicecan withstand. If the voltage across a circuit device exceeds thevoltage rating of the circuit device, the circuit device will bedamaged, and consequently the safety of the entire circuit will beendangered. Preferably, the switching control module 100 is alsoconfigured to control the switch unit 1 to switch off after the firstpositive half cycle of the current flow through the switch unit 1 afterthe switch unit 1 switches on, and the voltage applied to the switchunit 1 at the time the switch unit 1 switches off is lower than thevoltage rating of the switch unit 1. Thus, with the current sustainmenteffect of the freewheeling circuit 20 and by choosing the switching-offopportunity of the switch unit 1 appropriately, damage to the switchunit 1 resulted from high induced voltage on the current storagecomponent L1 in the loop can be further avoided, and the heating circuitis safer, and the adverse effect to the entire circuit can be reduced.Moreover, by choosing the switching-off opportunity of the switch unit 1appropriately, the induced voltage on the current storage component L1can be reduced to some extent, and therefore the requirement for currentsustainment capability of the freewheeling circuit 20 can be reduced, sothat the freewheeling circuit 20 can be implemented with components thathave lower characteristic parameters such as power or capacity, etc.

Wherein: for example, the switching-off opportunity can be the timeinterval from the time the current flow through the switch unit 1reaches degree 30 before zero after the peak value in the negative halfcycle to the time the current flow reaches degree 30 after zero beforethe peak value in the next positive half cycle, and the switch unit 1can be switched off at any time within the said time interval. Ofcourse, the present invention is not limited to that. The specificswitching-off opportunity should be determined according to the voltagerating of the switch unit 1; for example, the time interval can be fromthe time the current flow through the switch unit 1 reaches degree 60before zero after the peak value in the negative half cycle to the timethe current flow reaches degree 60 after zero before the peak value inthe next positive half cycle, depending on the voltage rating of theswitch unit 1.

In the cyclic charge/discharge process of the battery E, since theenergy will not be charged back completely into the battery E when thebattery E is charged in reversed direction, the energy discharged fromthe battery E in the next discharge cycle in positive direction will bereduced, and therefore the heating efficiency of the heating circuitwill be degraded. Therefore, preferably, the switching control module100 is configured to control the switch unit 1 to switch off when thecurrent flow through the switch unit 1 reaches zero after the peak valuein the negative half cycle after the switch unit 1 switches on, so as toimprove the heating efficiency of the heating circuit, and minimize theinduced voltage on the current storage component L1, and therebyminimize the voltage applied to the switch unit 1 when the switch unit 1switches off, in order to prevent the damage of high induced voltage tothe switch unit 1.

In one embodiment of the present invention, the switching control module100 is configured to control the switch unit 1 to switch off before thecurrent flow through the switch unit 1 reaches zero after the peak valuein the negative half cycle after the switch unit 1 switches on. As shownin FIG. 7, the freewheeling circuit 20 can comprises a switch K20 and aone-way semiconductor component D20 connected in series with each other;the switching control module 100 is connected with the switch K20, andis configured to control the switch K20 to switch on after the switchunit 1 switches on and then switches off, and control the switch K20 toswitch off after the current flow to the battery E reaches a presetvalue of current (e.g., zero). The freewheeling circuit 20 can beconnected in parallel between the ends of the battery E; or, one end ofthe freewheeling circuit 20 can be connected between the switch K7 andthe one-way semiconductor component D12 in the second one-way branch ofthe switch unit 1 shown in FIG. 4, and the other end of the freewheelingcircuit 20 can be connected to the battery E.

The preset value of current is a value that will not make the voltageapplied to the switch unit 1 higher than or equal to the voltage ratingof the switch unit 1 at the time the switch unit 1 switches off, and canbe set according to the voltage rating of the switch unit 1.

In another embodiment of the present invention, the switching controlmodule 100 is configured to control the switch unit 1 to switch offafter the current flow through the switch unit 1 reaches zero before thepeak value in the positive half cycle of the switch unit 1 after theswitch unit 1 switches on. As shown in FIG. 8, the freewheeling circuit20 can comprise a one-way semiconductor component D21, a dampingcomponent R21, and a charge storage component C21, the one-waysemiconductor component D21 and the damping component R21 are connectedin parallel with each other, and then connected in series with thecharge storage component C21; after the switch unit 1 switches on andthen switches off, the current storage component L1 can sustain thecurrent flow via the one-way semiconductor component D21 and the chargestorage component C21; the damping component R21 is configured torelease the energy stored in the charge storage component C21. Thefreewheeling circuit 20 can be connected in parallel between the ends ofthe battery E; or, one end of the freewheeling circuit 20 can beconnected between the switch K6 and the one-way semiconductor componentD11 in the first one-way branch of the switch unit 1 shown in FIG. 4,and the other end of the freewheeling circuit 20 can be connected to thebattery E.

Due to the fact that the current flow in the loop will be very low(i.e., approximate to zero) if the switch unit 1 is controlled to switchoff near the zero point of current flow through the switch unit 1 afterthe peak value in the negative half cycle, the voltage applied to theswitch unit 1 will be lower than the voltage rating of the switch unit 1at the time the switch unit 1 switches off near the zero point. As aresult, the requirement for current sustainment capability of thefreewheeling circuit 20 can be minimized, or even the freewheelingcircuit 20 can be omitted in the loop. Through a limited number oftests, those skilled in the art can obtain the range of switching-offtime interval of switch unit 1, in which the voltage applied to theswitch unit 1 is lower than the voltage rating of the switch unit 1 atthe time the switch unit 1 switches off.

The energy superposition unit is connected with the energy storagecircuit, and is configured to superpose the energy in the energy storagecircuit with the energy in the battery E after the switch unit 1switches on and then switches off, so that the discharging current inthe heating circuit will be increased when the switch unit 1 iscontrolled to switch on at the next time, and thereby the workingefficiency of the heating circuit is improved.

In one embodiment of the present invention, as shown in FIG. 9, theenergy superposition unit comprises a polarity inversion unit 102, whichis connected with the energy storage circuit, and is configured toinvert the voltage polarity of the charge storage component C1 after theswitch unit 1 switches on and then switches off; since the voltage ofthe charge storage component C1 can be superposed in series with thevoltage of the battery E after polarity inversion, the dischargingcurrent in the heating circuit will be increased when the switch unit 1switches on at the next time.

In one embodiment of the polarity inversion unit 102, as shown in FIG.10, the polarity inversion unit 102 comprises a single-pole double-throwswitch J1 and a single-pole double-throw switch J2 located on the twoends of the charge storage component C1 respectively; the input wires ofthe single-pole double-throw switch J1 are connected in the energystorage circuit, the first output wire of the single-pole double-throwswitch J1 is connected with the first pole plate of the charge storagecomponent C1, and the second output wire of the single-pole double-throwswitch J1 is connected with the second pole plate of the charge storagecomponent C1; the input wires of the single-pole double-throw switch J2are connected in the energy storage circuit, the first output wire ofthe single-pole double-throw switch J2 is connected with the second poleplate of the charge storage component C1, and the second output wire ofthe single-pole double-throw switch J2 is connected with the first poleplate of the charge storage component C1; the switching control module100 is also connected with the single-pole double-throw switch J1 andsingle-pole double-throw switch J2 respectively, and is configured toinvert the voltage polarity of the charge storage component C1 byaltering the connection relationships between the respective input wiresand output wires of the single-pole double-throw switch J1 and thesingle-pole double-throw switch J2.

According to this embodiment, the connection relationships between therespective input wires and output wires of the single-pole double-throwswitch J1 and single-pole double-throw switch J2 can be set in advance,so that the input wires of the single-pole double-throw switch J1 areconnected with the first output wire of the switch unit 1 and the inputwires of the single-pole double-throw switch J2 are connected with thefirst output wire of the switch unit 1 when the switch unit 1 switcheson; the input wires of the single-pole double-throw switch J1 areswitched to connect with the second output wire of the switch unit 1 andthe input wires of the single-pole double-throw switch J2 are switchedto connect with the second output wire of the switch unit 1 undercontrol of the switching control module 100 when the switch unit 1switches off, and thereby the voltage polarity of the charge storagecomponent C1 is inverted.

As another embodiment of the polarity inversion unit 102, as shown inFIG. 11, the polarity inversion unit 102 comprises a one-waysemiconductor component D3, a current storage component L2, and a switchK9; the charge storage component C1, current storage component L2, andswitch K9 are connected sequentially in series to form a loop; theone-way semiconductor component D3 is connected in series between thecharge storage component C1 and the current storage component L2 orbetween the current storage component L2 and the switch K9; theswitching control module 100 is also connected with the switch K9, andis configured to invert the voltage polarity of the charge storagecomponent C1 by controlling the switch K9 to switch on.

According to the above embodiment, when the switch unit 1 switches off,the switch K9 can be controlled to switch on by the switching controlmodule 100, and thereby the charge storage component C1, one-waysemiconductor component D3, current storage component L2, and switch K9form a LC oscillation loop, and the charge storage component C1discharges through the current storage component L2, thus, the voltagepolarity of the charge storage component C1 will be inverted when thecurrent flowing through the current storage component L2 reaches zeroafter the current in the oscillation circuit flows through the positivehalf cycle.

As yet another embodiment of the polarity inversion unit 102, as shownin FIG. 12, the polarity inversion unit 102 comprises a first DC-DCmodule 2 and a charge storage component C2; the first DC-DC module 2 isconnected with the charge storage component C1 and the charge storagecomponent C2 respectively; the switching control module 100 is alsoconnected with the first DC-DC module 2, and is configured to transferthe energy in the charge storage component C1 to the charge storagecomponent C2 by controlling the operation of the first DC-DC module 2,and then transfer the energy in the charge storage component C2 back tothe charge storage component C1, so as to invert the voltage polarity ofthe charge storage component C1.

The first DC-DC module 2 is a DC-DC (direct current to direct current)conversion circuit for voltage polarity inversion commonly used in thefield. Certain embodiments of the present invention do not impose anylimitation to the specific circuit structure of the first DC-DC module2, as long as the module can accomplish voltage polarity inversion ofthe charge storage component C1. Those skilled in the art can add,substitute, or delete the components in the circuit as needed.

FIG. 13 shows one embodiment of the first DC-DC module 2 provided in thepresent invention. As shown in FIG. 13, the first DC-DC module 2comprises: a two-way switch Q1, a two-way switch Q2, a two-way switchQ3, a two-way switch Q4, a first transformer T1, a one-way semiconductorcomponent D4, a one-way semiconductor component D5, a current storagecomponent L3, a two-way switch Q5, a two-way switch Q6, a secondtransformer T2, a one-way semiconductor component D6, a one-waysemiconductor component D7, and a one-way semiconductor component D8.

In the embodiment, the two-way switch Q1, two-way switch Q2, two-wayswitch Q3, and two-way switch Q4 are MOSFETs, and the two-way switch Q5and two-way switch Q6 are IGBTs.

The Pin 1, 4, and 5 of the first transformer T1 are dotted terminals,and the pin 2 and 3 of the second transformer T2 are dotted terminals.

Wherein: the positive electrode of the one-way semiconductor componentD7 is connected with the end ‘a’ of the charge storage component C1, andthe negative electrode of the one-way semiconductor component D7 isconnected with the drain electrodes of the two-way switch Q1 and two-wayswitch Q2, respectively; the source electrode of the two-way switch Q1is connected with the drain electrode of the two-way switch Q3, and thesource electrode of the two-way switch Q2 is connected with the drainelectrode of the two-way switch Q4; the source electrodes of the two-wayswitch Q3 and two-way switch Q4 are connected with the end ‘b’ of thecharge storage component C1 respectively. Thus, a full-bridge circuit isformed, here, the voltage polarity of end ‘a’ of the charge storagecomponent C1 is positive, while the voltage polarity of end ‘b’ of thecharge storage component C1 is negative.

In the full-bridge circuit, the two-way switch Q1, two-way switch Q2constitute the upper bridge arm, while the two-way switch Q3 and two-wayswitch Q4 constitute the lower bridge arm. The full-bridge circuit isconnected with the charge storage component C2 via the first transformerT1; the pin 1 of the first transformer T1 is connected with the firstnode N1, the pin 2 of the first transformer T1 is connected with thesecond node N2, the pin 3 and pin 5 of the first transformer T1 areconnected to the positive electrode of the one-way semiconductorcomponent D4 and the positive electrode of the one-way semiconductorcomponent D5 respectively; the negative electrode of one-waysemiconductor component D4 and the negative electrode of one-waysemiconductor component D5 are connected with one end of the currentstorage component L3, and the other end of the current storage componentL3 is connected with the end ‘d’ of the charge storage component C2; thepin 4 of the transformer T1 is connected with the end ‘c’ of the chargestorage component C2, the positive electrode of the one-waysemiconductor component D8 is connected with the end ‘d’ of the chargestorage component C2, and the negative electrode of the one-waysemiconductor component D8 is connected with the end ‘b’ of the chargestorage component C1; here, the voltage polarity of end ‘c’ of thecharge storage component C2 is negative, while the voltage polarity ofend ‘d’ of the charge storage component C2 is positive.

Wherein: the end ‘c’ of the charge storage component C2 is connectedwith the emitter electrode of the two-way switch Q5, the collectorelectrode of the two-way switch Q5 is connected with the pin 2 of thetransformer T2, the pin 1 of the transformer T2 is connected with end‘a’ of the charge storage component C1, the pin 4 of the transformer T2is connected with end ‘a’ of the charge storage component C1, the pin 3of the transformer T2 is connected with the positive electrode of theone-way semiconductor component D6, the negative electrode of theone-way semiconductor component D6 is connected with the collectorelectrode of the two-way switch Q6, and the emitter electrode of thetwo-way switch Q6 is connected with the end ‘b’ of the charge storagecomponent C2.

Wherein: the two-way switch Q1, two-way switch Q2, two-way switch Q3,two-way switch Q4, two-way switch Q5, and two-way switch Q6 arecontrolled by the switching control module 100 respectively to switch onand switch off.

Hereafter the working process of the first DC-DC module 2 will bedescribed:

1. After the switch unit 1 switches off, the switching control module100 controls the two-way switch Q5 and two-way switch Q6 to switch off,and controls the two-way switch Q1 and two-way switch Q4 to switch on atthe same time to form phase A; controls the two-way switch Q2 andtwo-way switch Q3 to switch on at the same time to form phase B. Thus,by controlling the phase A and phase B to switch on alternately, afull-bridge circuit is formed;

2. When the full-bridge circuit operates, the energy in the chargestorage component C1 is transferred through the first transformer T1,one-way semiconductor component D4, one-way semiconductor component D5,and current storage component L3 to the charge storage component C2;now, the voltage polarity of end ‘c’ of the charge storage component C2is negative, while the voltage polarity of end ‘d’ of the charge storagecomponent C2 is positive.

3. The switching control module 100 controls the two-way switch Q5 toswitch on, and therefore a path from the charge storage component C1 tothe charge storage component C2 is formed via the second transformer T2and the one-way semiconductor component D8, thus, the energy in thecharge storage component C2 is transferred back to the charge storagecomponent C1, wherein: some energy will be stored in the secondtransformer T2, Now, the switching control module 100 controls thetwo-way switch Q5 to switch off and controls the two-way switch Q6 toswitch on, and therefore the energy stored in the second transformer T2is transferred to the charge storage component C1 by the secondtransformer T2 and the one-way semiconductor component D6; now, thevoltage polarity of the charge storage component C1 is inverted suchthat end ‘a’ is negative and end ‘b’ is positive. Thus, the purpose ofinverting the voltage polarity of the charge storage component C1 isattained.

In one embodiment of the present invention, the working efficiency ofthe heating circuit can be improved by superposing the energy in thecharge storage component C1 with the energy in the battery E directly,or superposing the remaining energy in the charge storage component C1with the energy in the battery E after some energy in the charge storagecomponent C1 is consumed.

Therefore, as shown in FIG. 14, the heating circuit further comprises anenergy consumption unit, which is connected with the charge storagecomponent C1, and is configured to consume the energy in the chargestorage component C1 after the switch unit 1 switches on and thenswitches off and before the energy in the energy superposition unit issuperposed.

In one embodiment of the present invention, as shown in FIG. 15, theenergy consumption unit comprises a voltage control unit 101, which isconfigured to convert the voltage across the charge storage component C1to a predetermined voltage value after the switch unit 1 switches on andthen switches off and before the energy superposition unit performsenergy superposition. The predetermined voltage value can be set asneeded.

As shown in FIG. 15, the voltage control unit 101 comprises a dampingcomponent R5 and a switch K8, wherein: the damping component R5 andswitch K8 are connected in series with each other and then connected inparallel across the charge storage component C1; the switching controlmodule 100 is also connected with the switch K8, and is configured tocontrol the switch K8 to switch on after the switch unit 1 switches onand then switches off. Thus, the energy in the charge storage componentC1 can be consumed via the damping component R5.

The switching control module 100 can be a separate controller, which, byusing internal program setting, enables ON/OFF control of differentexternal switches; or, the switching control module 100 can be aplurality of controllers, for example, a switching control module 100can be set for each external switch correspondingly; or, the pluralityof switching control modules 100 can be integrated into an assembly.Certain embodiments of the present invention do not impose anylimitation to the forms of implementation of the switching controlmodule 100.

Hereafter the working principle of the embodiments of heating circuitfor battery E will be described briefly with reference to FIGS. 16-21.It should be noted that though the features and components of certainembodiments of the present invention are described specifically withreference to FIGS. 16-21, each feature or component can be usedseparately without other features and components, or can be used incombination or not in combination with other features and components.The embodiments of the heating circuit for battery E provided in thepresent invention are not limited to those shown in FIGS. 16-21. Inaddition, the time intervals between the time periods in the waveformdiagram shown in the drawings can be adjusted as needed, according tothe actual circumstance.

In the heating circuit for battery E shown in FIG. 16, the switch K6 andone-way semiconductor component D11 are connected in series toconstitute the first one-way branch of the switch unit; the one-waysemiconductor component D12 and switch K7 are connected in series toconstitute the second one-way branch of the switch unit 1, the switchunit 1, damping component R1, charge storage component C1, and currentstorage component L1 are connected in series, the one-way semiconductorcomponent D3, current storage component L2, and switch K9 constitute apolarity inversion unit 102, the one-way semiconductor component D20 andthe switch K20 constitute a freewheeling circuit 20, the switchingcontrol module 100 can control ON/OFF of the switch K6, the switch K7,the switch K9, and the switch K20. FIG. 17 shows a waveform sequencediagram corresponding to the heating circuit shown in FIG. 16, wherein:VC1 refers to the voltage across the charge storage component C1,I_(main) refers to the current flow through the switch unit 1, IL2refers to the current flow in the polarity inversion circuit, IC1 refersto the current flow through the charge storage component C1, and ID20refers to the current flow through the one-way semiconductor componentD20. The working process of the heating circuit shown in FIG. 16 is asfollows:

the switching control module 100 controls the switch K6 to switch on,and thus the battery E discharges in positive direction through the loopcomposed by the battery E, the switch K6, the one-way semiconductorcomponent D11, and the charge storage component C1 (in the time periodt1 shown in FIG. 17);

the switching control module 100 controls the switch K6 to switch offwhen the current flow reaches zero after the peak value in the firstpositive half cycle;

the switching control module 100 controls the switch K7 to switch on,and the battery E is charged in reversed direction through the loopcomposed by the battery E, the charge storage component C1, the switchK7, and the semiconductor device D12; the switching control module 100controls the switch K7 to switch off when the current flow reachesdegree 24 before zero after the peak value in the first negative halfcycle (in the time period t2 shown in FIG. 17);

the switching control module 100 controls the switch K20 to switch onwhen it controls the switch K7 to switch off, and thus the currentstorage component L1 sustains the current flow via the switch K20 andthe one-way semiconductor component D20; the switching control module100 controls the switch K20 to switch off when the current flow to thebattery E reaches zero (in the time period t3 shown in FIG. 17);

the switching control module 100 controls the switch K9 to switch on,and thus the charge storage component C1 discharges through the loopcomposed by the one-way semiconductor component D3, the current storagecomponent L2, and the switch K9, and thereby attain the purpose ofvoltage polarity inversion; then, the switching control module 100controls the switch K9 to switch off (in the time period t4 shown inFIG. 17);

repeat step a) to step e); the battery E is heated up continuously whileit discharges and is charged, till the battery E meets the heating stopcondition.

In the heating circuit for battery E shown in FIG. 18, the switch K6 andthe one-way semiconductor component D11 are connected in series toconstitute the first one-way branch of the switch unit 1; the one-waysemiconductor component D12 and switch K7 are connected in series toconstitute the second one-way branch of the switch unit 1, the switchunit 1, the damping component R1, the charge storage component C1, andthe current storage component L1 are connected in series, the one-waysemiconductor component D3, the current storage component L2, and theswitch K9 constitute a polarity inversion unit 102, the one-waysemiconductor component D21, the damping component R21, and the chargestorage component C21 constitute a freewheeling circuit 20, theswitching control module 100 can control ON/OFF of the switch K6, theswitch K7, and the switch K9. FIG. 19 shows a waveform sequence diagramcorresponding to the heating circuit shown in FIG. 18, wherein: VC1refers to the voltage across the charge storage component C1, I_(main)refers to the current flow through the switch unit 1, IL2 refers to thecurrent flow in the polarity inversion circuit, IC1 refers to thecurrent flow through the charge storage component C1, and IC21 refers tothe current flow through the charge storage component C21. The workingprocess of the heating circuit shown in FIG. 18 is as follows:

the switching control module 100 controls the switch K6 and the K7 toswitch on, and thus the battery E discharges in normal direction throughthe loop composed by the battery E, the switch K6, the one-waysemiconductor component D11, and the charge storage component C1 (in thetime period t1 shown in FIG. 19), and is charged in reversed directionthrough the loop composed by the battery E, the switch K7, the one-waysemiconductor component D12, and the charge storage component C1 (in thetime period t2 shown in FIG. 19);

the switching control module 100 controls the switch K6 and the K7 toswitch off when the current flow reaches degree 25 after zero before thepeak value in the second positive half cycle (in the time period t3shown in FIG. 19); the current storage component L1 sustains the currentflow via the one-way semiconductor component D21 and the charge storagecomponent C21 (in the time period t4 shown in FIG. 19);

the switching control module 100 controls the switch K9 to switch on,and thus the charge storage component C1 discharge through the loopcomposed by the one-way semiconductor component D3, the current storagecomponent L2, and the switch K9, and attain the purpose of voltagepolarity inversion; then, the switching control module 100 controls theswitch K9 to switch off (in the time period t5 shown in FIG. 19);

Repeat step a) to step c); the battery E is heated up continuously whileit discharges and is charged, till the battery E meets the heating stopcondition.

It should be noted that there is also current flow in the freewheelingcircuit 20 shown in FIG. 18 in the time period t1 and t2. To illustrateclearly the purpose of the freewheeling circuit 20 in the heatingcircuit provided in certain embodiments of the present invention, onlythe current flow in the time periods when the effect of the freewheelingcircuit 20 is operative is shown in FIG. 19, but the current flow in thefreewheeling circuit 20 in the time period t1 and t2 is omitted, toavoid confusion.

In the heating circuit for battery F shown in FIG. 20, a two-way switchK3 is used to form the switch unit 1, the energy storage circuitcomprises a current storage component L1 and a charge storage componentC1, the damping component R1 and the switch unit 1 are connected inseries with the energy storage circuit, the one-way semiconductorcomponent D3, the current storage component L2, and the switch K9constitute a polarity inversion unit 102, the switching control module100 can control the switch K9 and the two-way switch K3 to switch on andswitch off. FIG. 21 is a timing sequence diagram of the waveformcorresponding to the heating circuit shown in FIG. 20, wherein: VC1refers the voltage value across the charge storage component C1,I_(main) refers to the value of current flow through the two-way switchK3, and IL2 refers to the value of current in the polarity inversioncircuit. The working process of the heating circuit shown in FIG. 20 isas follows:

the switching control module 100 controls the two-way switch K3 toswitch on, and the energy storage circuit starts operation, as indicatedby the time period t1 in FIG. 20; the battery E discharges in normaldirection and is charged in reversed direction through the loop composedby the battery E, the two-way switch K3, and the charge storagecomponent C1 (in the time period t1 shown in FIG. 21);

the switching control module 100 controls the two-way switch K3 toswitch off when the current flow through the two-way switch K3 reacheszero after the peak value in the negative half cycle (i.e., when thereverse current reaches zero);

the switching control module 100 controls the switch K9 to switch on,and thus the polarity inversion unit 102 starts operation; the chargestorage component C1 discharges through the loop composed by the one-waysemiconductor component D3, the current storage component L2, and theswitch K9, and attain the purpose of voltage polarity inversion; then,the switching control module 100 controls the switch K9 to switch off(in the time period t2 shown in FIG. 21);

Repeat step a) to step c); the battery E is heated up continuously whileit discharges and is charged, till the battery E meets the heating stopcondition.

In the heating circuit shown in FIG. 20, since the two-way switch K3switches off when the current flow through the two-way switch K3 reacheszero after the peak value in the negative half cycle (i.e., the reversecurrent reaches zero), the freewheeling circuit 20 does not play itsrole of current sustainment. Therefore, the freewheeling circuit 20 isomitted in FIG. 21.

The heating circuit provided in certain embodiments of the presentinvention can improve the charge/discharge performance of a battery. Inaddition, since an energy storage circuit is connected with the batteryin series in the heating circuit, the safety problem related with shortcircuit caused by failures of the switch unit can be avoided when thebattery is heated due to the existence of the charge storage componentconnected in series, and therefore the battery can be protectedeffectively.

In addition, in the heating circuit provided in certain embodiments ofthe present invention, since the current flow in the battery can besustained by the freewheeling circuit, the current flow in the currentstorage component will have no abrupt change when the switch unitswitches off, and thus no high voltage will be induced when the switchunit switches off; as a result, damage to the switch unit resulted fromhigh induced voltage on the current storage component in the loop can beprevented, and the heating circuit is safer, and the adverse effect tothe entire circuit can be reduced.

In addition, an energy superposition unit is provided in the heatingcircuit in certain embodiments of the present invention, and the energysuperposition unit can superpose the energy in the energy storagecircuit with the energy in the battery after the switch unit switchesoff; thus, the discharging current in the heating circuit will beincreased when the switch unit is controlled to switch on at the nexttime, and therefore the working efficiency of the heating circuit isimproved.

For example, some or all components of various embodiments of thepresent invention each are, individually and/or in combination with atleast another component, implemented using one or more softwarecomponents, one or more hardware components, and/or one or morecombinations of software and hardware components. In another example,some or all components of various embodiments of the present inventioneach are, individually and/or in combination with at least anothercomponent, implemented in one or more circuits, such as one or moreanalog circuits and/or one or more digital circuits.

While some embodiments of the present invention are described above withreference to the accompanying drawings, the present invention is notlimited to the details of those embodiments. Those skilled in the artcan make modifications and variations, without departing from the spiritof the present invention. However, all these modifications andvariations shall be deemed as falling into the scope of the presentinvention.

In addition, it should be noted that the specific technical featuresdescribed in the above embodiments can be combined in any appropriateway, provided that there is no conflict. To avoid unnecessaryrepetition, certain possible combinations are not describedspecifically. Moreover, the different embodiments of the presentinvention can be combined as needed, as long as the combinations do notdeviate from the spirit of the present invention. However, suchcombinations shall also be deemed as falling into the scope of thepresent invention.

Hence, although specific embodiments of the present invention have beendescribed, it will be understood by those of skill in the art that thereare other embodiments that are equivalent to the described embodiments.Accordingly, it is to be understood that the invention is not to belimited by the specific illustrated embodiments, but only by the scopeof the appended claims.

What is claimed is:
 1. A battery heating circuit, comprising a switchunit, a switching control module, a damping component, an energy storagecircuit, a freewheeling circuit, and an energy superposition unit,wherein: the energy storage circuit is configured to connect with thebattery to form a loop, and comprises a current storage component and acharge storage component; the damping component, the switch unit, thecurrent storage component, and the charge storage component areconnected in series; the switching control module is connected with theswitch unit, and is configured to switch on the switch unit so as toallow current flow from the battery to the energy storage circuit andfrom the energy storage circuit to the battery and to switch off theswitch unit so as to stop the current flow; the energy superpositionunit is connected across the energy storage circuit, and is configuredto superpose the energy in the energy storage circuit with the energy inthe battery after the switch unit switches on and then switches off; thefreewheeling circuit is configured to form a serial loop with thebattery and the current storage component to sustain current flow in thebattery after the switch unit switches on and then switches off.
 2. Theheating circuit according to claim 1, wherein: the damping component isa parasitic resistance in the battery, and the current storage componentis a parasitic inductance in the battery.
 3. The heating circuitaccording to claim 1, wherein: the damping component is a resistor, thecurrent storage component is an inductor, and the charge storagecomponent is a capacitor.
 4. The heating circuit according to claim 3,wherein: the energy superposition unit comprises a polarity inversionunit, which is connected with the energy storage circuit, and isconfigured to invert the voltage polarity of the charge storagecomponent after the switch unit switches on and then switches off. 5.The heating circuit according to claim 4, wherein: the polarityinversion unit comprises a first single-pole double-throw switch and asecond single-pole double-throw switch located on the two ends of thecharge storage component respectively; the input wires of the firstsingle-pole double-throw switch are connected in the energy storagecircuit, the first output wire of the first single-pole double-throwswitch is connected with the first pole plate of the charge storagecomponent, and the second output wire of the first single-poledouble-throw switch is connected with the second pole plate of thecharge storage component; the input wires of the second single-poledouble-throw switch are connected in the energy storage circuit, thefirst output wire of the second single-pole double-throw switch isconnected with the second pole plate of the charge storage component,and the second output wire of the second single-pole double-throw switchis connected with the first pole plate of the charge storage component;and the switching control module is also connected with the firstsingle-pole double-throw switch and second single-pole double-throwswitch respectively, and is configured to invert the voltage polarity ofthe charge storage component by altering the connection relationshipsbetween the respective input wires and output wires of the firstsingle-pole double-throw switch and the second single-pole double-throwswitch.
 6. The heating circuit according to claim 4, wherein: thepolarity inversion unit comprises a one-way semiconductor component, asecond current storage component, and a switch; the charge storagecomponent, second current storage component, and switch are connectedsequentially in series to form a loop; the one-way semiconductorcomponent is connected in series between the charge storage componentand the second current storage component or between the second currentstorage component and the switch; and the switching control module isalso connected with the switch, and is configured to invert the voltagepolarity of the charge storage component by controlling the switch toswitch on.
 7. The heating circuit according to claim 4, wherein: thepolarity inversion unit comprises a DC-DC module and a second chargestorage component; the DC-DC module is connected with the charge storagecomponent and the second charge storage component respectively; and theswitching control module is also connected with the DC-DC module, and isconfigured to transfer the energy in the charge storage component to thesecond charge storage component by controlling the operation of theDC-DC module, and then transfer the energy in the second charge storagecomponent back to the charge storage component, so as to invert thevoltage polarity of the charge storage component.
 8. The heating circuitaccording to claim 1, wherein: the switch unit is a two-way switch. 9.The heating circuit according to claim 1, wherein: the switch unitcomprises a first one-way branch configured to enable energy flow fromthe battery to the energy storage circuit and a second one-way branchconfigured to enable energy flow from the energy storage circuit to thebattery; and the switching control module is connected to the firstone-way branch and the second one-way branch, respectively, and isconfigured to control switching the switch unit on or off by controllingturning the connected branches on or off.
 10. The heating circuitaccording to claim 9, wherein: the switch unit comprises a first two-wayswitch and a second two-way switch, the first two-way switch and thesecond two-way switch are connected in series opposite to each other toform the first one-way branch and the second one-way branch; and theswitching control module is connected with the first two-way switch andsecond two-way switch respectively, and is configured to controlswitching the first one-way branch and the second one-way branch on oroff by controlling switching the first two-way switch and second two-wayswitch on or off.
 11. A battery heating circuit, comprising a switchunit, a switching control module, a damping component, an energy storagecircuit, a freewheeling circuit, and an energy superposition unit,wherein: the energy storage circuit is configured to connect with thebattery to form a loop, and comprises a current storage component and acharge storage component; the damping component, the switch unit, thecurrent storage component, and the charge storage component areconnected in series; the switching control module is connected with theswitch unit, and is configured to switch on the switch unit so as toallow current flow between the battery and the energy storage circuitand to switch off the switch unit so as to stop the current flow; theenergy superposition unit is connected with the energy storage circuit,and is configured to superpose the energy in the energy storage circuitwith the energy in the battery after the switch unit switches on andthen switches off; the freewheeling circuit is configured to form aserial loop with the battery and the current storage component tosustain current flow in the battery after the switch unit switches onand then switches off; the switch unit comprises a first one-way branchconfigured to enable energy flow from the battery to the energy storagecircuit and a second one-way branch configured to enable energy flowfrom the energy storage circuit to the battery; and the switchingcontrol module is connected to the first one-way branch and the secondone-way branch, respectively, and is configured to control switching theswitch unit on or off by controlling turning the connected branches onor off; wherein: the switch unit comprises a first switch, a firstone-way semiconductor component, a second switch, and a second one-waysemiconductor component, the first switch and the first one-waysemiconductor component are connected with each other in series toconstitute the first one-way branch; the second switch and the secondone-way semiconductor component are connected in series with each otherto constitute the second one-way branch; and the switching controlmodule is connected with the first switch and the second switch, and isconfigured to control turning the first one-way branch and the secondone-way branch on or off by controlling switching the first switch andthe second switch on or off.
 12. The heating circuit according to claim9, wherein: the switch unit further comprises a resistor connected inseries with the first one-way branch and/or the second one-way branch.13. The heating circuit according to claim 1, wherein: the freewheelingcircuit comprises a switch and a one-way semiconductor componentconnected in series with each other; and the switching control module isconnected with the switch, and is configured to control the switch toswitch on after the switch unit switches on and then switches off, andcontrol the switch to switch off when the current flow to the batteryreaches a preset value of current.
 14. The heating circuit according toclaim 1, wherein: the freewheeling circuit comprises a one-waysemiconductor component, a second damping component, and a second chargestorage component; and the one-way semiconductor component and thesecond damping component are connected in parallel with each other, andthen connected in series with the second charge storage component. 15.The heating circuit according to claim 1, wherein: the switching controlmodule is also configured to control the switch unit to switch off afterthe first positive half cycle of the current flow through the switchunit after the switch unit switches on, and the voltage applied to theswitch unit at the time the switch unit switches off is lower than thevoltage rating of the switch unit.
 16. The heating circuit according toclaim 15, wherein: the switching control module is configured to controlthe switch unit to switch off when the current flow through the switchunit reaches zero after the peak value in the negative half cycle afterthe switch unit switches on.
 17. The heating circuit according to claim1, wherein: the heating circuit further comprises an energy consumptionunit, which is connected with the charge storage component and isconfigured to consume the energy in the charge storage component afterthe switch unit switches on and then switches off and before the energysuperposition unit performs energy superposition.
 18. The heatingcircuit according to claim 17, wherein: the energy consumption unitcomprises a voltage control unit, which is connected with the chargestorage component, and configured to convert the voltage across thecharge storage component to a predetermined voltage value after theswitch unit switches on and then switches off and before the energysuperposition unit performs energy superposition.
 19. The heatingcircuit according to claim 18, wherein: the voltage control unitcomprises a second damping component and a switch, the second dampingcomponent and the switch are connected with each other in series, andthen connected in parallel across the charge storage component; and theswitching control module is also connected with the switch, and isconfigured to control the switch to switch on after the switch unitswitches on and then switches off.